The present invention relates generally to dental restorations and more specifically to bonding layers for ceramic components used in dental restorations and methods of making thereof. The invention is also directed to high strength ceramic components embedded in composite materials or ceramic materials for use as dental materials.
Strength and reliability are important factors to consider when manufacturing dental restorations. Dental restorations must be able to withstand the normal mastication forces and stresses that exist within an oral environment. Different stresses are observed during mastication of different types of food, which can be experimentally measured by placing, for example, a strain gauge in inlays on the tooth. Stresses differ depending not only on the type of food, but also on the individual. For example, stress values may range from 570 to 2300 lb/inch2 for a single chewing thrust on a piece of meat and from 950 to 2400 lb/inch2 for a single thrust on a biscuit. The physical properties of dental restorations must be adequate to withstand the stresses applied by the repetitive forces of mastication.
Ceramic materials have proven to be reliable in the fabrication of single unit dental restorations. U.S. Pat. No. 4,798,536 to Katz and an article by Kabbert and Knode entitled xe2x80x9cInceram: Testing a New Ceramic Materialxe2x80x9d, Vol.4, pp 87-97 (1993) each disclose ceramic compositions having leucite therein to provide strength and reliability to dental restorations. The strength of the materials is in the area of 170 MPa which is much higher than that of conventional porcelain which exhibits strengths of about 70 MPa. Nevertheless, the strength and/or toughness values of the aforementioned ceramic materials may not be adequate for the fabrication of multiple unit restorations.
There is a need to provide high strength, ceramic restorations having structural integrity and reliability and optimum bonding properties. It is desirable to produce high strength ceramic restorations which are compatible with a wide range of cost-effective polymeric based dental materials.
These and other objects and advantages are accomplished by the composition and method of manufacture of the present invention directed to high strength ceramic components for use in dental applications. In accordance with one embodiment herein, a bonding layer is disposed on a ceramic component to increase the bonding properties of the ceramic component in order that the ceramic component may better bond to a resin material, ceramic material or composite material. Moreover, the bonding layer provides strength to the ceramic component by forming a compressive layer thereon.
In accordance with another embodiment herein, a ceramic component is partially or fully embedded or encapsulated in composite material. The ceramic component is bonded to the composite material either by mechanical means, chemical means or both. The composite material may be placed directly on the ceramic component. Alternatively, the structural component is coated with a bonding layer to provide adhesion between the composite or like material and the structural component.
In accordance with yet another embodiment herein, silicon dioxide is deposited on the surface of the structural component in the form of colloidal silica, silane, tetra ethyl orthosilicate, or a similar silica precursor and heat treated to form a bonding layer which bonds the structural component to a resin, ceramic or composite material.
In accordance with still yet another embodiment, one or more layers of ceramic material are disposed on a high strength ceramic component to provide a dental restoration. The ceramic material may be applied in the form of powder, putty, tape or a pellet.
The resultant structural component is useful in the fabrication of dental appliances and restorations such as orthodontic retainers, bridges, space maintainers, tooth replacement appliances and splints.